| Resently years, plant fiber-reinforced polylactic acid biodegradable composites have been a rising environment-friendly material, with the adventages of high strength, impact resistance, damproof, sound-insulation and biodegradation. It can be widely used in national defence, architecture, transportation, project and varied areas in daily life. But the high flammability of both the plant fiber and polyactic acid makes the composites combustible. Thus, the research on flame retardance and smoke suppression of the composites has caught more and more attentions and also becomes a point in composite study.The plant fiber made of bamboo processing residues and dwarf bamboo are used as the reinforced material, and the biodegrade resin-polylactic acid is used as the base material. Then a processing of compression molding was carried out to make the bamboo fiber and polylactic acid into composites. In the research, the best mass ratio of raw materials is studied, as well as the influences and menchanisms of three different types of flame retardant and smoke suppressant to modify the composites which contains aliminium hydroxide (ATH), ammonium polyphosphate (APP), and APP+ ATH.(1) The bamboo fiber/PLA composite was prepared by different mass fractions of fibers (20%,30%,40%), and then was tested on the mechanical property. The results illustrated that with the increasing of mass fraction of the fiber, the mechanical property of the composite decreased gradually. In consideration of the mechanical property and the cost, in the study, the quality ratio between bamboo fiber and PLA was 30:70, which leading to a tensile strength at 31Mpa, and an impact strength at 6.8 KJ.m-2.(2) The biodegradable composites materials made from bamboo fiber and poly-lactic acid were modified by inorganic environmental retardant-ATH, and properties of the materials were tested and characterized. The results showed that mechanical property slightly decreases with the increasing of ATH content. Thermal stability and carbon yield of that increase in contrary. The introduction of ATH has an adverse effect on release of heat and gas, which has a great effect on flame retardancy of the composite material. With comprehensive comparative analysis, ATH content was 25%, integrated performance was best.(3) The composites materials was prepared by molding technology mixed with ammonium polyphosphate (APP), bamboo fiber and poly-lactic acid, and properties of the materials were tested and characterized. The results showed that mechanical property slightly decreases with the increasing of APP content. Thermal stability and carbon yield of that are increasing in contrary. In addition, the introduction of APP has an adverse effect on release of heat. And release rate of combustion heat is 150kw.m-2 in average declining nearly 50%. But, the introduction of APP increased the release of gas in a certain degree. With comprehensive comparative analysis, APP is taken as an individual retardant, it’s content was 20%, integrated performance was best.(4) Compared and analyed the mechanics performance, thermal stability and flame retardant and smoke suppression performance of two kinds of fire-retardant bamboo fiber/polylactic acid composites modified by ATH and APP, The result shows that the APP has stronger inhibitory thermal effect on the composite, but also accompanied with large amount of smoke, the hot suppression effect of ATH composite is no better than APP, but it has good smoke suppression effect According to the idea of complementary advantages, we can use the APP+ATH composite flame retardant to modify the bamboo fiber/polylactic acid composite. The results show that the use of flame retardant APP+ATH composite greatly improved the thermal stability of the composite and carbon residue rate. Compared with the composite which didn’t add flame retardant,the APP+ATH flame retardant makes the composite’s carbon residue rate increased more than 2 times at 600℃, with the increase rate of ATH content in the flame retardant, composite’s carbon residue rate gradually decreased.The processing of the APP+ATH in the combustion has obvious inhibitory effect as well as strong smoke suppression effect to the bamboo fiber/polylactic acid composite. When the quality ratio of APP and ATH in the flame retardant reach to 7:3, composite’s flame retardant and smoke suppression has the best effect. Based on the analysis of the composite’s mechanics performance, thermal stability,flame retardant and smoke suppression performance, the best quality ratio of APP and ATH is 7:3,when we add them into the bamboo fiber/polylactic acid (PLA) composite materials use to do flame retardant and smoke suppression.(5) We can get the conclusing that flame retardant and smoke suppression type of bamboo fiber/polylactic acid composites modified by ATH and APP has a bad Waterproof properties through the analysis of it, Tensile strength of the composite material downs to nearly 90% on average, bibulous rate reached over 5% after 4 days. As a result, this type of flame retardant and smoke suppression bamboo fiber/polylactic acid composites need a further waterproof processing as a outdoor material.(6) On the basis of various performance tests and characterized on three type flame retardant smoke suppression composites modified by ATH, APP and APP+ATH, observed and compared the tensile section and charcoal layer microstructure after burning of the flame retardant and smoke suppression type of bamboo fiber/polylactic acid composites by using scanning electron microscopy,fully verified the flame retardant APP and ATH different mechanism in the process of combustion of the three type of flame retardant smoke suppression bamboo fiber/polylactic acid composites. |
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